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AZ31/7075 composite with the addition of Zn foil (about 100 μm in thickness) in the dissimilar material interface was successfully fabricated by pre-extrusion+caliber rolling composite process. The microstructure evolution especially for the composite interface was characterized by optical microscopy (OM), scanning electron microscopy (SEM) with energy dispersive spectrometer (EDS) and the microhardness test was also performed. The effect of the Zn intermediate layer on the product during the extrusion and caliber rolling was explored. The results show the hard 7075 Al alloy as the core can refine the grain size of AZ31 alloy. In addition, introducing Zn intermediate layer can reduce or completely avoid the formation of Mg-Al intermetallic compounds. The temperature increased by extrusion and deformation results in the remelting of eutectic Mg-Zn phase, and the diffusion of both elements from the solid to the liquid phase are accelerated. However, discontinuous cracks can be observed in the Mg-Zn diffusion layer but will be healed after caliber rolling. The MgZn2 intermetallic compound generated at Mg-Zn diffusion layer has high hardness (161HV), but the overall hardness of bonding layer is not changed a lot due to thinner thickness of the Mg-Zn diffusion layer after deformation.

This study deals with the problem of observer‐based finite‐time H∞ control for a class of one‐sided Lipschitz (OSL) singular systems with uncertainties. The parameter uncertainties are assumed to be time‐varying norm‐bounded appearing not only in both the state and output matrices but also in the non‐linear function. With the help of some special derivations and transformation, the sufficient conditions ensuring robust finite‐time boundedness of the closed‐loop system and satisfying the H∞ performance index are given for OSL singular systems in terms of linear matrix inequalities (LMIs). Based on these, the observer and controller dynamics can be simultaneously involved in the design at one step. Two convex optimisation problems subject to LMIs are formulated to optimise the desired performance indices of interest to us. Finally, two examples are given to demonstrate the effectiveness of the proposed methods. [ABSTRACT FROM AUTHOR]

This paper deals with the problem of robust normalization and delay-dependent H control for a class of singular Markovian jump systems with norm-bounded parameter uncertainties and time delay. A new impulsive and proportional-derivative control strategy with memory is presented, which results in a novel class of hybrid impulsive systems. Sufficient conditions are developed to guarantee that the resultant closed-loop system is not only robust normal and stochastically stable, but also satisfies a prescribed H performance level for all delays no larger than a given upper bound. In addition, the explicit expression of the desired impulsive control gains is also given together with the design approach. Finally, two numerical examples are provided to illustrate the effectiveness of the proposed methods. [ABSTRACT FROM AUTHOR]